My little research has found a number of references to the 67's 4p or SS with either the L48 or L30.?

Nope. No such thing as an SS Camaro with the 327.

However, if it's the 4P designation that's confusing you, yes, it was used with the SS 350 and the L30/M20 options. It WASN'T used to stipulate SS, but was only used as an instruction for Fisher Body to install the radius rod. More info HERE.

Check the CRG site under research topics for the full report on L30/M20's. Very informative to include some production estimates that are about as accurate as you will find. Not many made and far fewer left that are complete (motor-trans-rear). If your car is a true L30/M20 - keep it together and maybe we can bring some posting competition to the forum vs. all the boys with '69's and Z's!!!!!!!